textproduct: Rapid City

KEY MESSAGES

- Strong winds expected today, with elevated to critical fire weather conditions.

- Cooler today, but temperatures gradually warming up through the week.

UPDATE

Issued at 527 AM MDT Mon Jun 29 2026

Storms have exited the CWA and the Severe Thunderstorm Watch was cancelled early. Rest of the forecast still on track with the Wind Advisory for the western SD plains. Have issued a Red Flag Warning for portions of the northeastern WY plains RH into southwestern SD. Min RH will reach near 15% this afternoon to accompany the gusts of 40 to 55 mph. Isolated storms will be possible this afternoon across northwest SD. Some may be strong to severe.

UPDATE Issued at 1052 PM MDT Sun Jun 28 2026

A Severe Thunderstorm Watch is now in effect for portions of our south-central South Dakota plains overnight. Very strong deep- layer shear in excess of 65kts will favor supercells, and while a shallow stable layer may be present at the surface suggesting storms may be elevated, very thick mid-level CAPE profiles in forecast soundings with over 3,000 J/kg MUCAPE possible will support a very large hail threat. Convection may also be enhanced by gravity waves increasing a damaging wind threat with time, with some HRRR and RRFS guidance hinting at gusts over 80 MPH in far eastern portions of our CWA. A non-zero tornado risk exists as well with notable SRH, but the elevated nature of the storms may keep this risk low. Will also be watching for swaths of very heavy rain with storm training, with localized flash flooding not impossible...especially if storms train over areas that saw significant rainfall last night in our southern/eastern counties. Largely went with NBM and WPC guidance in the forecast, but adjusted PoPs and QPF to better match current radar trends and the new 00z HREF suite including CAMs. Breezy conditions remain expected Monday, and no changes were made to the ongoing WIND ADVISORY. These winds, along with minimum afternoon RH values of 12-18 percent, may support near-critical fire weather conditions especially from the Weston County area into the far southwestern South Dakota plains. Some areas have seen recent rainfall but may still carry critical fuels...confidence remains just low enough that we will continue to monitor these conditions and not issue a Red Flag Warning with this update.

DISCUSSION

(This Evening Through Sunday) Issued at 1208 PM MDT Sun Jun 28 2026

Current Water Vapor and upper air models show the upper low currently over north central MT, with southwest flow over the forecast area. 17Z Surface analysis shows a boundary running from northwestern SD down into southeastern WY. Winds are currently light out of the south to southwest. Radar has some light returns in northwestern SD moving northeast into ND.

Main concern in the near-term will be potential for severe thunderstorms tonight into Monday morning. Mostly dry conditions are expected this afternoon, but southeasterly LLJ ramps up this evening into the overnight hours, bringing moisture into the region. Surface low is expected to develop over northeastern CO and move northeastward into the area by tonight. As low enters the region and LLJ increases, strong to severe storms are expected to develop. While we could see some showers/storms develop in the early evening, HREF and HRRR show the stronger storms starting up between 03-06Z. CAMS currently show strong to severe storms developing in southwestern SD and the Black hills in this timeframe, then moving northeast. Thermal profiles will support elevated storms with hail being the main threat from these, however strong to severe wind gusts cannot be ruled out.

Monday will be dry but windy, as strong mixing will support wind gusts 45 to 55 mph. A Wind Advisory has been issued for much of western SD, including the foothills late morning into the early evening. Another shortwave is progged to move through the central/northern plains late Tuesday into Wednesday, supporting the potential for some showers/storms. Southwest flow continues though the week, with weak disturbances prompting near daily chances for at least isolated precipitation the latter half of the week. Upper high in southeastern CONUS also builds over the week, supporting a gradual warmup. Temperatures climbing into the 90s will be possible Thursday through Saturday.

AVIATION

(For the 18Z TAFS Through 18Z Tuesday) Issued At 1120 AM MDT Mon Jun 29 2026

VFR conditions are expected today. Isolated showers and storms this afternoon across NW SD where transient MVFR/IFR conditions are possible.

Gusty southwest winds expected this afternoon, strongest across NE WY and western SD plains where gusts 40 to 50 mph are expected. Winds will diminish after 02-03z this evening.

UNR WATCHES/WARNINGS/ADVISORIES

SD...Wind Advisory until 8 PM MDT this evening for SDZ012-013-025>027- 030-031-041-042-072>076. Red Flag Warning until 9 PM MDT this evening for SDZ322-325-326- 332. WY...Red Flag Warning until 9 PM MDT this evening for WYZ315-317.